JP2019052261A - Curable composition and cured product of the same - Google Patents

Abstract

To provide a curable composition which can form a cured product showing high mechanical characteristics (tensile strength, bending strength, and the like) and a low thermal expansion ratio, and where a cellulose nanofiber is uniformly dispersed.SOLUTION: A curable composition is prepared by combining a curable resin (A) with a modified cellulose nanofiber (B) to which a fluorene compound (B1) having an aryl group is bonded at 9,9 position. The fluorene compound (B1) may be a compound represented by the following formula (1). In formula, a ring Z represents an arene ring; Rand Rrepresent substituent groups; Xrepresents a hetero atom-containing functional group; k represents an integer of 0 to 4; n represents an integer of 1 or more; and p represents an integer of 0 or more.SELECTED DRAWING: None

Description

  The present invention relates to a curable composition comprising a heat or photocurable resin and cellulose nanofibers modified with a 9,9-bisarylfluorene skeleton, a method for producing the same, and a cured product of the curable composition (for example, And a cured product of a prepreg containing the curable composition and another fibrous reinforcing material.

  Cellulose nanofibers (cellulose nanofibers or CNFs) are fibers obtained by refining cellulose raw materials (wood, pulp, etc.), which are plant-derived resources, and are attracting attention as materials that have abundant resources and can reduce environmental impact. . The feature of cellulose nanofiber is that it is lightweight and has excellent mechanical properties (high strength, high elastic modulus, etc.) and thermal properties (low thermal expansion coefficient, etc.). As a composite material that has been added to a curable resin such as an epoxy resin to improve its properties, its use is being studied in various fields.

  Typical examples of such composite materials include printed wiring board materials that require high mechanical properties (such as tensile strength and bending strength) and low thermal expansion in the electric / electronic field. For example, Japanese Unexamined Patent Application Publication No. 2014-220344 (Patent Document 1) discloses a printed wiring board material including an epoxy compound, a phenol compound as a curing agent thereof, and cellulose nanofibers having a predetermined fiber diameter. . In the examples of this document, a printed wiring board material prepared by mixing a dispersion of cellulose nanofibers having a predetermined fiber diameter, an epoxy compound, a phenol compound, and the like is prepared. It describes that properties such as flammability and elongation at break are excellent. JP-A-2006-6131 (Patent Document 2) discloses a prepreg laminate in which a plurality of prepregs each having a predetermined reinforcing fiber and a base resin composition in which nanofibers are dispersed are stacked in a predetermined state. It is disclosed. This document describes that cellulose nanofibers can be used as nanofibers, and in Examples, it is described that the tensile strength of the laminate is improved by cellulose nanofibers.

  However, in these documents, since the affinity between the cellulose nanofiber and the resin is not so high, the reinforcing effect by the cellulose nanofiber cannot be sufficiently exhibited.

  On the other hand, JP-A-2006-79370 (Patent Document 3) has cellulose, at least one reactive group selected from a carboxyl group or a reactive derivative thereof and an epoxy group, and an aryl group at the 9th and 9th positions. A resin composition containing modified cellulose combined with a fluorene compound is disclosed. In this document, as a resin contained in the resin composition, a thermoplastic resin or a thermosetting resin (or photocurable resin) such as an epoxy resin is exemplified. In the examples, polylactic acid which is a thermoplastic resin is used. Is used.

  However, in this document, a resin composition containing a heat or photocurable resin and modified cellulose is not specifically prepared.

JP, 2014-220344, A (Claim 1, Example) JP-A-2006-6131 (Claims 1 and 7, Examples) JP-A-2016-79370 (claims, paragraphs [0092] [0093], Examples)

  Accordingly, an object of the present invention is to form a cured product exhibiting high mechanical properties (tensile strength, bending strength, etc.) and a low coefficient of thermal expansion, and a curable composition in which cellulose nanofibers are uniformly dispersed and its A manufacturing method, and a prepreg containing the curable composition, and a cured product thereof.

  Another object of the present invention is to provide a curable composition capable of forming a cured product excellent in adhesion (or adhesion) with a metal (for example, copper foil), a method for producing the same, and the curable composition. It is in providing the prepreg containing and its hardened | cured material.

  As a result of intensive studies to achieve the above-described problems, the present inventors have found that when a curable resin is combined with a modified cellulose nanofiber to which a compound having a 9,9-bis (aryl) fluorene skeleton is bonded, the dispersion usually occurs. Discovered that cellulose nanofibers can be uniformly dispersed even in difficult curable resins, and that the cured product exhibits high mechanical properties (tensile strength, bending strength, etc.) and low coefficient of thermal expansion. did.

  That is, the curable composition of the present invention includes a curable resin (A) and a modified cellulose nanofiber (B) to which a fluorene compound (B1) having an aryl group at the 9,9-position is bonded.

  The fluorene compound (B1) may be a compound represented by the following formula (1).

(In the formula, ring Z is an arene ring, R ¹ and R ² are substituents, X ¹ is a heteroatom-containing functional group, k is an integer of 0 to 4, n is an integer of 1 or more, and p is an integer of 0 or more. Show).

In the formula (1), X ¹ is a group-[(OA) _m1 -Y ¹ ] (wherein A is an alkylene group, Y ¹ is a hydroxyl group or a glycidyloxy group, and m1 represents an integer of 0 or more) It may be. The proportion of the fluorene compound (B1) may be about 0.01 to 25% by weight with respect to the total amount of the modified cellulose nanofiber (B). The average fiber diameter of the modified cellulose nanofiber (B) may be about 5 to 500 nm. The curable resin (A) may be an epoxy resin. The ratio of the modified cellulose nanofiber (B) may be, for example, about 0.1 to 20 parts by weight with respect to 100 parts by weight of the curable resin (A). The curable composition may further contain a solvent.

  The present invention includes the curable composition comprising a mixing step of mixing the curable resin (A) with the modified cellulose nanofiber (B) and / or a raw material thereof (component forming the modified cellulose nanofiber (B)). In which the raw material is a fluorene compound (B1) and an unmodified cellulose nanofiber (B2).

  The present invention also includes a prepreg further including the curable composition and a second fibrous reinforcing material other than the modified cellulose nanofiber (B). The second fibrous reinforcing material may be an inorganic fiber.

  Furthermore, this invention also includes the hardened | cured material of the said prepreg. In the cured product, the volume ratio of the modified cellulose nanofiber (B) may be about 0.1 to 10% by volume with respect to the entire cured product. The cured product may be a printed wiring board material.

  Since the curable resin composition of the present invention is combined with a modified cellulose nanofiber to which a compound having a 9,9-bis (aryl) fluorene skeleton is bonded, the cellulose nanofiber is uniformly dispersed in the curable resin. The cured product exhibits high mechanical properties (such as tensile strength and bending strength) and a low coefficient of thermal expansion. Further, the cured product is excellent in adhesion (or adhesion) with a metal (for example, copper foil).

FIG. 1 is a scanning electron micrograph of cellulose nanofibers used in the examples.

  The curable composition of the present invention comprises a modified cellulose nanofiber in which a curable resin (A) and a fluorene compound (B1) having an aryl group at the 9th and 9th positions (also simply referred to as fluorene compound (B1)) are bonded. B).

[Curable resin (A)]
The curable resin (A) may be a photocurable resin, but is usually a thermosetting resin in many cases. Typical thermosetting resins include, for example, phenolic resins (resol type phenolic resin, novolac type phenolic resin, etc.), amino resins (eg, urea resin, melamine resin, guanamine resin, etc.), furan resin, unsaturated polyester series. Resin, diallyl phthalate resin, vinyl ester resin (or epoxy (meth) acrylate resin), polyfunctional (meth) acrylate resin, epoxy resin, urethane resin, polyimide resin (for example, bismaleimide resin), silicone resin Etc. These curable resins (A) (thermosetting resins) can be used alone or in combination of two or more. Of these curable resins (A), epoxy resins are generally used.

  The epoxy resin is not particularly limited as long as it has two or more epoxy groups, and a conventional epoxy resin can be used. For example, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, cycloaliphatic type Examples thereof include an epoxy resin, a heterocyclic epoxy resin, and a bromine-containing epoxy resin.

  Examples of glycidyl ether type epoxy resins include bisphenol type epoxy resins [for example, bisphenols such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins (or their alkylene oxide additions). ) Diglycidyl ether, diglycidyl ether of biphenols such as p, p′-biphenol (or its alkylene oxide adduct), etc.]; novolak type epoxy resins (for example, phenol novolak type epoxy resins, cresol novolak type epoxy resins) Condensed polycyclic aromatic hydrocarbon-modified epoxy resin (for example, 1,6-bis (glycidyloxy) naphthalene); tetrakisphenol type epoxy resin (for example, teto) An epoxy resin having a 9,9-bisarylfluorene skeleton [eg, 9,9-bis (4-glycidyloxy-phenyl) fluorene, 9,9-bis (6-glycidyloxy) 2,9-bis (glycidyloxyaryl) fluorene such as 2-naphthyl) fluorene, 9,9-bis (5-glycidyloxy-1-naphthyl) fluorene, 9,9-bis [4- (2-glycidyloxy) Ethoxy) -phenyl] fluorene, 9,9-bis [4- (2-glycidyloxypropoxy) -phenyl] fluorene, 9,9-bis [4- (2- (2-glycidyloxyethoxy) ethoxy) -phenyl] Fluorene, 9,9-bis [6- (2-glycidyloxyethoxy) -2-naphthyl] fluorene Which of 9,9-bis [glycidyloxy (poly) alkoxyaryl] fluorene], and others. In the present specification and claims, “(poly) alkoxy” is used to mean including both an alkoxy group and a polyalkoxy group.

  Examples of the glycidyl ester type epoxy resin include diglycidyl esters of aromatic dicarboxylic acids such as diglycidyl phthalate; diglycidyl esters of hydrogenated aromatic dicarboxylic acids such as diglycidyl tetrahydrophthalate and diglycidyl hexahydrophthalate. Can be mentioned.

  Examples of the glycidylamine-type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, tetraglycidylmetaxylylenediamine, tetraglycidylbisaminomethylcyclohexane, and the like.

  Examples of the cycloaliphatic epoxy resin include 3- (3,4-epoxycyclohexyl) -8,9-epoxy-2,4-dioxaspiro [5.5] undecane, bis (3,4-epoxycyclohexylmethyl). Examples include adipate, (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexanecarboxylate, 4-vinylcyclohexene dioxide.

  Examples of the heterocyclic epoxy resin include isocyanurate type epoxy resins such as triglycidyl isocyanate, and hydantoin type epoxy resins such as diglycidyl hydantoin.

  Examples of the bromine-containing epoxy resin include tetrabromobisphenol A type epoxy resin, reaction product of bisphenol A type epoxy resin and tetrabromobisphenol A, reaction product of brominated phenol novolac resin and epichlorohydrin, diglycidyl tri And bromoaniline.

  These epoxy resins may be monomers or multimers (such as dimers and trimers). Moreover, these epoxy resins can also be used individually or in combination of 2 or more types. Of these epoxy resins, glycidyl ether type epoxy resins such as bisphenol type epoxy resins (for example, bisphenol A type epoxy resins) are generally used.

[Modified cellulose nanofiber (B)]
The modified cellulose nanofiber (B) (also referred to as the first fibrous reinforcing material) is an unmodified cellulose nanofiber (or raw material cellulose nanofiber) (B2) in which the fluorene compound (B1) having an aryl group at the 9,9-position is used. It is a fiber bonded to [simply referred to as cellulose nanofiber (B2)].

(Fluorene compound (B1))
The fluorene compound (B1) having an aryl group at the 9,9-position is a phase for uniformly dispersing cellulose nanofibers in the curable resin (A) as a functional group constituting the modified cellulose nanofibers (B). Functions as a solubilizer or dispersant. That is, the fluorene compound (B1) is high in mechanical properties (tensile strength, bending strength, etc.) and low in the cured product, either due to chemical interaction (or high affinity) with the curable resin (A). Thermal expansion coefficient can be realized.

  Such a fluorene compound is a compound having a 9,9-bisarylfluorene skeleton, and may be, for example, a fluorene compound represented by the formula (1).

  In the formula (1), examples of the arene ring represented by the ring Z include a monocyclic arene ring such as a benzene ring, a polycyclic arene ring, and the like. The polycyclic arene ring includes a condensed polycyclic arene. A ring (fused polycyclic aromatic hydrocarbon ring), a ring assembly arene ring (ring assembly aromatic hydrocarbon ring) and the like are included.

Examples of the condensed polycyclic arene ring include a condensed bicyclic arene ring (for example, a condensed bicyclic C _10-16 arene ring such as a naphthalene ring), a condensed tricyclic arene (for example, an anthracene ring, a phenanthrene ring, etc.) And condensed bi- to tetracyclic arene rings. Preferred examples of the condensed polycyclic arene ring include a naphthalene ring and an anthracene ring, and a naphthalene ring is particularly preferable.

Examples of the ring-assembled arene ring include, for example, a bialene ring [for example, a bi-C _6-12 arene ring such as a biphenyl ring, a binaphthyl ring, and a phenylnaphthalene ring (for example, a 1-phenylnaphthalene ring, a 2-phenylnaphthalene ring, etc.)] And a terarene ring (for example, a tel C _6-12 arene ring such as a terphenylene ring). Preferred ring-assembled arene rings include bi-C _6-10 arene rings, particularly biphenyl rings.

The two rings Z substituted at the 9-position of fluorene may be different or the same, but are usually the same ring in many cases. Among the rings Z, for example, a C _6-12 arene ring such as a benzene ring, a naphthalene ring and a biphenyl ring, and a C _6-10 arene ring (particularly a benzene ring) is preferable.

  In addition, the substitution position of the ring Z substituted by 9-position of fluorene is not specifically limited. For example, when the ring Z is a naphthalene ring, the group corresponding to the ring Z substituted at the 9-position of fluorene may be a 1-naphthyl group, a 2-naphthyl group, or the like.

Examples of the hetero atom-containing functional group represented by X ¹ include a functional group having at least one selected from oxygen, sulfur and nitrogen atoms as a hetero atom. The number of heteroatoms contained in such a functional group is not particularly limited, but may be usually 1 to 3, preferably 1 or 2.

Examples of the functional group include a group-[(OA) _m1 -Y ¹ ] (wherein Y ¹ is a hydroxyl group, a glycidyloxy group, an amino group, an N-substituted amino group, a mercapto group, or 2,3-epithio A propyloxy group, A is an alkylene group, m1 is an integer of 0 or more, a group — (CH ₂ ) _m2 —COOR ³ (wherein R ³ is a hydrogen atom or an alkyl group, and m2 is 0 or more) Is an integer).

In the group-[(OA) _m1 -Y ¹ ], examples of the N-substituted amino group for Y ¹ include an N-monoalkylamino group (N-monoC _1-4 alkylamino) such as a methylamino group and an ethylamino group. Groups), N-monohydroxyalkylamino groups such as hydroxyethylamino groups (N-monohydroxy _C1-4 alkylamino groups, etc.) and the like.

The alkylene group A includes a linear or branched alkylene group. Examples of the linear alkylene group include linear C _2-6 alkylene groups such as an ethylene group, trimethylene group, and tetramethylene group ( Preferably, a linear C _2-4 alkylene group, more preferably a linear C _2-3 alkylene group, particularly an ethylene group) can be exemplified. Examples of the branched alkylene group include a propylene group, 1,2- Examples thereof include branched C _3-6 alkylene groups such as butanediyl group and 1,3-butanediyl group (preferably branched C _3-4 alkylene group, particularly propylene group).

  M1 which shows the repeating number (average addition mole number) of an oxyalkylene group (OA) can be selected from the range of 0 or an integer greater than or equal to 1 (for example, about 0-15, preferably about 0-10), for example, 0-8. (E.g. 1 to 8), preferably 0 to 5 (e.g. 1 to 5), more preferably 0 to 4 (e.g. 1 to 4), especially 0 to 3 (e.g. 1 to 3). Ordinarily, it may be about 0 to 2 (for example, 0 or 1). When m1 is 2 or more, the types of the two or more alkylene groups A may be the same or different. Further, the type of alkylene group A may be the same or different in the same or different ring Z.

In the group — (CH ₂ ) _m2 —COOR ³ , the alkyl group represented by R ³ is a linear or branched chain such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, or a t-butyl group. An example is a C _1-6 alkyl group. Preferred alkyl groups are linear or branched C _1-4 alkyl groups, especially C _1-2 alkyl groups. M2 which shows the repeating number (average addition mole number) of a methylene group may be 0 or an integer greater than or equal to 1 (for example, 1 to 6, preferably 1 to 4, more preferably about 1 to 2). m2 may usually be 0 or 1-2.

Of these groups X ¹ , the group-[(OA) _m1 -Y ¹ ] (wherein A is an alkylene group, Y ¹ is a hydroxyl group or glycidyloxy group, and m1 is an integer of 0 or more) is preferable, A group in which Y ¹ is a glycidyloxy group-[(OA) _m1 -Y ¹ ] [wherein A is a C _2-6 alkylene group such as an ethylene group (for example, a C _2-4 alkylene group, particularly a C _2-3 alkylene); Group), Y ¹ is a glycidyloxy group, and m1 is an integer of 0 to 5 (for example, 0 or 1)].

In the formula (1), n indicating the number of the group X ¹ substituted on the ring Z is 0 or more (preferably 1 or more), preferably 1 to 3, more preferably 1 or 2 (particularly 1). There may be. The number of substitutions n may be the same or different in each ring Z.

The group X ¹ can be substituted at an appropriate position of the ring Z. For example, when the ring Z is a benzene ring, the 2-position, 3-position and / or 4-position (eg 3-position) of the phenyl group And / or 4-position, especially 4-position), and when ring Z is a naphthalene ring, it may be substituted at any of the 5- to 8-positions of the naphthyl group. In many cases, for example, the 1-position or 2-position of the naphthalene ring is substituted with respect to the 9-position of fluorene (substitution in terms of 1-naphthyl or 2-naphthyl), and 1,5 In many cases, the group X ¹ is substituted by a relationship such as -position, 2,6-position (particularly, when n is 1, 2,6-position). Moreover, when n is 2 or more, the substitution position is not particularly limited. In addition, in the ring assembly arene ring Z, the substitution position of the group X ¹ is not particularly limited, and for example, the arene ring bonded to the 9-position of fluorene and / or the arene ring adjacent to the arene ring is substituted. Also good. For example, the 3-position or 4-position of the biphenyl ring Z may be bonded to the 9-position of fluorene, and when the 3-position of the biphenyl ring Z is bonded to the 9-position of fluorene, the group X ¹ The substitution position may be any of 2-, 4-, 5-, 6-, 2'-, 3'-, and 4'-positions, and is usually 6-, 3'-, and 4'-positions. , Preferably 6-, 4'-position (particularly 6-position) may be substituted. When the 4-position of the biphenyl ring Z is bonded to the 9-position of fluorene, the substitution position of the group X ¹ is any of the 2-, 3-, 2′-, 3′-, and 4′-positions. In general, it may be substituted at 2-, 3′-, 4′-position, preferably 2-, 4′-position (particularly 2-position).

In the formula (1), examples of the substituent R ² include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, butyl group, Linear or branched C _1-10 alkyl group such as isobutyl group, s-butyl group, t-butyl group, preferably linear or branched C _1-6 alkyl group, more preferably linear Or a branched C _1-4 alkyl group, etc.), a cycloalkyl group (C _5-10 cycloalkyl group such as a cyclopentyl group, cyclohexyl group, etc.), an aryl group [phenyl group, alkylphenyl group (methylphenyl group ( tolyl), a dimethylphenyl group (xylyl)), biphenyl group, _{C 6-12} aryl group, an aralkyl group (benzyl group such as a naphthyl group, off Nechiru such _{C 6-10} aryl _{-C 1-4} alkyl group such group), an alkoxy group (e.g., methoxy group, an ethoxy group, a propoxy group, n- butoxy group, isobutoxy group, a linear, such as t- butoxy Or a branched C _1-10 alkoxy group, etc.), a cycloalkoxy group (eg, a C _5-10 cycloalkyloxy group such as a cyclohexyloxy group), an aryloxy group (eg, a C _6-10 such as a phenoxy group). Aryloxy group etc.), aralkyloxy group (eg C _6-10 aryl-C _1-4 alkyloxy group such as benzyloxy group), alkylthio group (eg methylthio group, ethylthio group, propylthio group, n-butylthio) Group, C _1-10 alkylthio group such as t-butylthio group), cycloalkylthio group (example) Eg to such _{C 5-10} cycloalkylthio groups such as cyclohexylthio group cyclohexylene), an arylthio group (e.g., a _{C 6-10} arylthio group such as thiophenoxy group), aralkylthio group (eg, _C, such as benzylthio _{6- 10} aryl-C _1-4 alkylthio group, etc.), acyl group (eg, C _1-6 acyl group such as acetyl group), nitro group, cyano group, substituted amino group [eg, dialkylamino group (eg, dimethylamino group) and di C _1-4 alkylamino group such group), dialkyl carbonyl amino group (e.g., bis (C _1-4 alkyl such as diacetylamino groups - carbonyl) amino group, etc.), etc.], and others.

Of these substituents R ² , typically, a halogen atom, a hydrocarbon group (alkyl group, cycloalkyl group, aryl group, aralkyl group), alkoxy group, acyl group, nitro group, cyano group, substituted amino group Etc. Preferred substituents R ² include alkyl groups, aryl groups (such as phenyl groups), alkoxy groups (such as linear or branched C _1-4 alkoxy groups such as methoxy groups), particularly alkyl groups (particularly methyl). Straight chain or branched C _1-4 alkyl group such as a group) is preferred. In addition, when the substituent R ² is an aryl group, the substituent R ² may form the ring assembly arene ring together with the ring Z. The type of the substituent R ² may be the same or different in the same or different ring Z.

The coefficient p of the substituent R ² can be appropriately selected according to the type of the ring Z and the like, and may be an integer of about 0 to 8, for example, an integer of 0 to 4, preferably 0 to 3 (for example, 0 to 2). ), More preferably 0 or 1. In particular, when p is 1, the ring Z may be a benzene ring, a naphthalene ring or a biphenyl ring, and the substituent R ² may be a methyl group.

Examples of the substituent R ¹ include a cyano group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.), a carboxyl group, an alkoxycarbonyl group (for example, a C _1-4 alkoxy-carbonyl group such as a methoxycarbonyl group), an alkyl, etc. Groups (such as C _1-6 alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, and t-butyl groups), aryl groups (such as C _6-10 aryl groups such as phenyl groups), and the like. It is done.

Among these substituents R ¹ , a linear or branched C _1-4 alkyl group (particularly, a C _1-3 alkyl group such as a methyl group), a carboxyl group or a C _1-2 alkoxy-carbonyl group, cyano A group and a halogen atom are preferred. The substitution number k is an integer of 0 to 4 (for example, 0 to 3), preferably an integer of 0 to 2 (for example, 0 or 1), particularly 0. The number of substitutions k may be the same or different from each other. When k is 2 or more, the types of the two or more substituents R ¹ may be the same or different from each other, and two benzene rings of a fluorene ring The types of substituents R ¹ substituted on may be the same as or different from each other. Further, the substitution position of the substituent R ¹ is not particularly limited, and may be, for example, 2-position to 7-position (2-position, 3-position and / or 7-position, etc.) of the fluorene ring.

Among these, as a preferable fluorene compound, when group X ¹ is group-[(OA) _m1 -Y ¹ ] (wherein Y ¹ represents a hydroxyl group), for example, 9,9-bis ( 4-hydroxyphenyl) fluorene, 9,9-bis (6-hydroxy-2-naphthyl) fluorene, 9,9-bis (5-hydroxy-1-naphthyl) fluorene such as 9,9-bis (hydroxy _{C 6- 12} aryl) fluorene; 9,9-bis (di or trihydroxy C _6-12 aryl) fluorene such as 9,9-bis (3,4-dihydroxyphenyl) fluorene; 9,9-bis (3-methyl-4 9,9-bis (C _1-4 alkyl- _{hydroxyC 6-12} aryl) fluorene such as -hydroxyphenyl) fluorene; 9,9-bis (3-phenyl-4-) 9,9-bis (C _6-12 aryl-hydroxy C _6-12 aryl) fluorene such as hydroxyphenyl) fluorene, 9,9-bis (4-phenyl-3-hydroxyphenyl) fluorene; 9,9-bis [ 4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [6- (2-hydroxyethoxy) -2-naphthyl] fluorene, 9,9-bis [5- (2-hydroxyethoxy) -1- 9,9-bis (hydroxy (poly) C _2-4 alkoxy-C _6-12 aryl) fluorene such as naphthyl] fluorene; 9,9-bis [3-methyl-4- (2-hydroxyethoxy) phenyl] fluorene 9,9-bis (C _1-4 alkyl-hydroxy (poly) C _2-4 alkoxy-C _6-12 aryl) fluorene such as 9,9-bis (C) such as 9-bis [3-phenyl-4- (2-hydroxyethoxy) phenyl] fluorene, 9,9-bis [4-phenyl-3- (2-hydroxyethoxy) phenyl] fluorene _6-12 aryl-hydroxy (poly) C _2-4 alkoxy-C _6-12 aryl) fluorene and the like.

As a preferred fluorene compound when the group X ¹ is a group-[(OA) _m1 -Y ¹ ] (wherein Y ¹ represents a glycidyloxy group), 9,9-bis (glycidyloxyaryl) fluorene For example, 9,9-bis (3-glycidyloxyphenyl) fluorene, 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (5-glycidyloxy-1-naphthyl) fluorene, 9,9-bis (glycidyloxy C _6-10 aryl) fluorene such as 9-bis (6-glycidyloxy-2-naphthyl) fluorene; 9,9-bis ([glycidyloxy (poly) alkoxyaryl] fluorene, for example 9,9-bis [4- (2-glycidyloxy-ethoxy) phenyl] fluorene, 9,9-bis [4- (2- Glycidyloxy-propoxy) phenyl] fluorene, 9,9-bis [5- (2-glycidyloxy-ethoxy) -1-naphthyl] fluorene, 9,9-bis [6- (2-glycidyloxy-ethoxy) -2 9,9-bis [glycidyloxy (poly) C _2-4 alkoxy C _6-10 aryl] fluorene such as naphthyl] fluorene; 9,9-bis (alkyl-glycidyloxyaryl) fluorene, for example 9,9- 9,9-bis (C _1-4 alkyl-glycidyloxy C _6-10 aryl) fluorene such as bis (3-methyl-4-glycidyloxyphenyl) fluorene; 9,9-bis [alkyl-glycidyloxy (poly) Alkoxyaryl] fluorene such as 9,9-bis [3-methyl-4- (2-glycidyloxy) Shietokishi) phenyl] fluorene such as 9,9-bis _{[C 1-4} alkyl - glycidyloxy _{(poly) C 2-4} alkoxy _{C 6-10} aryl] fluorene; 9,9-bis (aryl - glycidyloxy aryl) fluorene 9,9-bis (C _6-10 ) such as 9,9-bis (3-phenyl-4-glycidyloxyphenyl) fluorene and 9,9-bis (4-phenyl-3-glycidyloxyphenyl) fluorene Aryl-glycidyloxy C _6-10 aryl) fluorene; 9,9-bis [aryl-glycidyloxy (poly) alkoxyaryl] fluorene, such as 9,9-bis [3-phenyl-4- (2-glycidyloxyethoxy) ) Phenyl] fluorene, 9,9-bis [4-phenyl-3- (2-glycidyl) Kishietokishi) phenyl] fluorene such as 9,9-bis _{[C 6-10} aryl - glycidyloxy _{(poly) C 2-4} alkoxy _{C 6-10} aryl] fluorene; 9,9-bis [di (glycidyloxy) aryl] Fluorene, for example, 9,9-bis [di (glycidyloxy) C _6-10 aryl] fluorene such as 9,9-bis [3,4-di (glycidyloxy) phenyl] fluorene; 9,9-bis [di (Glycidyloxy (poly) alkoxy) aryl] fluorene, for example, 9,9-bis [di (glycidyloxy (poly) such as 9,9-bis [3,4-di (2-glycidyloxyethoxy) phenyl] fluorene C _2-4 alkoxy) C _6-10 aryl] fluorene and the like.

  These fluorene compounds (B1) can be used alone or in combination of two or more. Note that “(poly) alkoxy” is used to mean both an alkoxy group and a polyalkoxy group.

(Cellulose nanofiber (B2))
Cellulose nanofibers (or cellulose nanofibers) (B2) constituting the modified cellulose nanofiber (B) are cellulose fibers obtained by refining cellulose (cellulose raw material) to the nano order (or microfibrillation), and microorganism-derived nanometers. It is a cellulose fiber of the size. Examples of the cellulose raw material include pulps having a low content of non-cellulosic components such as lignin and hemicellulose, such as plant-derived cellulose raw materials {for example, wood [for example, conifers (pine, fir, spruce, tsuga, cedar, etc.), hardwoods] (Beech, hippopotamus, poplar, maple, etc.)], herbaceous plants [hempies (hemp, flax, manila hemp, ramie, etc.), straw, bagasse, mitsumata, etc.], seed hair fibers (cotton linter, bombacs cotton, capock, etc.) ), Bamboo, sugarcane, etc.}, animal-derived cellulose raw materials (eg, squirt cellulose), bacteria-derived cellulose raw materials (eg, cellulose contained in Nata de Coco), and the like. These cellulose raw materials can be used alone or in combination of two or more. Of these cellulose raw materials, wood pulp (for example, softwood pulp, hardwood pulp, etc.), pulp derived from seed hair fibers (for example, cotton linter pulp) and the like are preferable. The pulp may be a mechanical pulp obtained by mechanically treating a pulp material, but a chemical pulp obtained by chemically treating a pulp material is preferable because the content of non-cellulosic components is small.

  The average fiber diameter and average fiber length of the cellulose nanofiber (or raw material cellulose nanofiber) (B2) can be selected so that the average fiber diameter and average fiber length of the modified cellulose nanofiber (B) are within the ranges described below. The average fiber diameter, the average fiber length, and the ratio of the average fiber length to the average fiber diameter (aspect ratio) of the cellulose nanofibers may be the same as the range of the modified cellulose nanofibers described later, and are generally substantially the same.

  Cellulose nanofibers may be highly crystalline cellulose (or cellulose fibers), and the crystallinity of cellulose is, for example, 40 to 100% (for example, 50 to 100%), preferably 60 to 95%. More preferably, it may be about 70 to 90% (particularly 75 to 90%), and the crystallinity may be usually 60% or more. Examples of the crystal structure of cellulose include I-type, II-type, III-type, and IV-type, and an I-type crystal structure excellent in linear expansion characteristics and elastic modulus is preferable.

(Modified cellulose nanofiber (B) and production method thereof)
The modified cellulose nanofiber (or modified cellulose nanofiber) (B) is a cellulose derivative in which the cellulose nanofiber (B2) and the fluorene compound (B1) are bonded.

The form of chemical modification (or bonding) of the modified cellulose nanofiber (B) is not particularly limited. For example, when the fluorene compound (B1) is a fluorene compound represented by the formula (1), the fluorene compound (B1) The reactive group (heteroatom-containing functional group) can be appropriately selected. Specifically, in the formula (1), when Y ¹ is a hydroxyl group, an ether of the hydroxyl group and / or carboxyl group of cellulose nanofiber and the hydroxyl group of the fluorene compound represented by the formula (1). It may be a bond and / or an ester bond, and when Y ¹ is a glycidyloxy group, the hydroxyl group and / or carboxyl group of the cellulose nanofiber and the glycidyl group of the fluorene compound represented by the formula (1) It may be an ether bond and / or an ester bond. In addition, the carboxyl group of a cellulose nanofiber may be formed in the manufacture processes, such as a pulp.

  The modified cellulose nanofiber (B) may be produced by reacting the raw material cellulose nanofiber (B2) and the fluorene compound (B1) in the presence of a predetermined catalyst. In the curable resin (A), You may manufacture by making it react in the process in which raw material cellulose nanofiber (B2) and the said fluorene compound (B1) are mixed.

  Although the ratio of raw material cellulose nanofiber (B2) can be selected according to the reactive group of a fluorene compound (B1), it is 0.1-500 weight part (for example, with respect to 100 weight part of fluorene compounds (B1)), for example. 1 to 300 parts by weight), for example, it may be about 5 to 200 parts by weight (particularly 10 to 150 parts by weight).

  When using a catalyst, a catalyst can also be selected according to the reactive group of a fluorene compound, and when a reactive group is a hydroxyl group, you may utilize an acid catalyst. Examples of the acid catalyst include Bronsted acid, for example, inorganic acid such as sulfuric acid, hydrochloric acid, and phosphoric acid, organic acid such as p-toluenesulfonic acid, and solid acid [for example, heteropolyacid (tungsten heteropolyacid, molybdenum heteropolyacid, etc. ), Cation exchange resins (strong acid cation exchange resins having sulfonic acid groups, fluorine-containing cation exchange resins having sulfonic acid groups, weak acid cation exchange resins having carboxylic acid groups, etc.)]. These acid catalysts can be used alone or in combination of two or more.

  When the reactive group is a glycidyl group, a base catalyst may be used. The base catalyst may be either an inorganic base or an organic base. Examples of the inorganic base include alkali metal hydroxides (sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates, alkali metal bicarbonates. Etc. can be exemplified. Organic bases include tertiary amines such as trialkylamines (trimethylamine, triethylamine, etc.), alkanolamines (triethanolamine, dimethylaminoethanol, etc.), heterocyclic amines (morpholine, etc.), hexamethylenetetramine, diaza Bicycloundecene (DBU), diazabicyclononene (DBN), 1,4-diazabicyclo [2.2.2] octane (DABCO) and the like can be mentioned. These base catalysts can also be used alone or in combination of two or more.

  Although the usage-amount of a catalyst can be selected according to the kind of catalyst, it can select suitably from the range of about 0.01-100 weight part with respect to 100 weight part of raw material cellulose nanofibers (B2), Usually, 0.01 to 20 parts by weight (eg 0.1 to 18 parts by weight), preferably 0.5 to 18 parts by weight (eg 1 to 17 parts by weight), more preferably 3 to 15 parts by weight (particularly 5 to 15 parts) Part by weight).

  When a catalyst is used, the reaction may be performed in the absence of an organic solvent, but is usually performed in the presence of an organic solvent. The organic solvent may be impregnated in the raw material cellulose nanofiber (B2), but is often reacted in a dispersion system in which the raw material cellulose nanofiber (B2) is dispersed in the organic solvent. When the raw material cellulose nanofibers (B2) and the fluorene compound (B1) are reacted in a dispersion system in which the raw material cellulose nanofibers (B2) are dispersed in an organic solvent, they can be reacted uniformly. The modified cellulose nanofiber (B) obtained by such a method has high handleability and dispersibility.

  When the raw material cellulose nanofibers (B2) (in particular, microfibrillated fibers, nanofibers having an average fiber diameter of nanometer size) are dried, the fibers may be entangled and cannot be redispersed. Therefore, usually, the raw material cellulose nanofiber (B2) is often marketed as a water-impregnated or aqueous dispersion. In such an aqueous dispersion, a conventional solvent replacement method for replacing the water in the aqueous dispersion with an organic solvent, for example, adding an aqueous solvent to the aqueous dispersion of the raw cellulose nanofiber (B2), and mixing the raw cellulose nanofiber After separating the fiber (B2) (or removing the solvent), a dispersion liquid in which the raw material cellulose nanofibers (B2) are dispersed in the organic solvent can be prepared by a method of repeatedly adding and mixing the organic solvent. When a water-soluble organic solvent having a boiling point higher than that of water is used, the solvent can be replaced by removing water by distillation (including azeotropic distillation).

Examples of the water-soluble organic solvent include alcohols (C _1-4 alkanols such as methanol, ethanol, propanol and isopropanol), ethers (cyclic ethers such as dioxane and tetrahydrofuran), ketones (acetone and the like), amides, and the like. (Dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, etc.), sulfoxides (dimethylsulfoxide, etc.), alkanediols (for example, C _2-4 alkanediols such as ethylene glycol, propylene glycol), cellosolves (methyl cellosolve, Ethyl cellosolve), carbitols (such as ethyl carbitol), carbonates (such as ethylene carbonate, propylene carbonate, dimethyl carbonate). It is. These solvents may be used alone or in combination of two or more.

  In the cellulose-containing dispersion obtained by solvent replacement using a water-soluble organic solvent, the water-soluble organic solvent can be replaced with a water-insoluble organic solvent in the same manner as described above. Water-insoluble organic solvents include ethers (dialkyl ethers such as diethyl ether and diisopropyl ether), esters (such as methyl acetate, ethyl acetate, and butyl acetate), ketones (such as methyl ethyl ketone and methyl isobutyl ketone), and nitriles ( Benzonitrile, etc.), cellosolve acetates, carbitol acetates, hydrocarbons (aliphatic hydrocarbons such as hexane, octane, cyclohexane, aromatic hydrocarbons such as toluene), halogenated hydrocarbons (dichloromethane, chloroform) Carbon tetrachloride, dichloroethane, trichloroethylene, etc.). These water-insoluble organic solvents can also be used alone or in combination of two or more.

  Of these organic solvents, aprotic solvents, particularly aprotic polar solvents (for example, ethers, ketones, amides, sulfoxides, etc.) are preferable.

The solubility parameter (SP value, (cal / cm) ² ) of the organic solvent (eg, aprotic polar solvent) may be about 8 to 15 (eg, 8.5 to 15), and usually 9 to 14 About 5 (for example, 10 to 14.5).

  The solid content concentration of the raw material cellulose nanofiber (B2) in the dispersion is, for example, 0.01 to 30% by weight (for example, 0.1 to 20% by weight), preferably 1 to 15% by weight, and more preferably 3%. It may be about ˜12% by weight (for example, 5 to 10% by weight). If the solid content concentration is too low, the reaction efficiency may decrease.

  When using a catalyst, the reaction may be carried out under reduced pressure, but is usually carried out under pressure or normal pressure in many cases. The reaction temperature can be appropriately selected depending on the boiling point of the solvent, and may be, for example, about 50 to 200 ° C. (for example, 70 to 170 ° C.), preferably about 80 to 150 ° C. (for example, 100 to 130 ° C.). The reaction may be performed under reflux of the solvent. Moreover, reaction time is not specifically limited, For example, it is about 10 minutes-48 hours (for example, 30 minutes-24 hours). Furthermore, the reaction can be carried out in air or in an atmosphere of an inert gas (such as a rare gas such as nitrogen or argon). The reaction may be performed while stirring the reaction system.

  In addition, it may replace with raw material cellulose nanofiber (B2), and may use raw material cellulose fiber which is not nanometer size. When using raw material cellulose fibers that are not nanometer-sized, react with the fluorene compound (B1) while applying mechanical shearing force to the raw material cellulose fibers to prepare modified cellulose nanofibers (B) that are refined cellulose. Alternatively, the modified cellulose nanofiber (B) refined by defibration after completion of the reaction may be prepared, or these methods may be combined.

  The modified cellulose nanofiber (B) produced by the reaction using a catalyst may be separated and purified by a conventional method (for example, centrifugation, filtration, concentration, extraction, etc.). For example, a solvent capable of dissolving at least the fluorene compound (B1) is added to the reaction mixture, the unreacted fluorene compound is removed by a separation method (conventional method) such as centrifugation, filtration, and extraction, followed by separation and purification. Also good. The separation operation can be performed a plurality of times (for example, about 2 to 5 times). Furthermore, powdered modified cellulose fibers can be obtained by drying the separated and purified modified cellulose under heating and / or under reduced pressure or normal pressure.

  In addition, when the modified cellulose obtained by repeatedly removing the unreacted fluorene compound by the separation method or the like is analyzed by a method such as Raman analysis, there are a peak derived from the cellulose and a peak derived from the fluorene compound. It can be confirmed that the fluorene compound is bonded.

  On the other hand, when the modified cellulose nanofiber (B) is produced by mixing in the curable resin (A), the fluorene compound (B1) and the raw material cellulose nanofiber ( The modified cellulose nanofiber (B) is obtained by mixing B2) and the catalyst as necessary with the curable resin (A). However, the modified cellulose nanofiber (B) modified with the fluorene compound (B1) in advance is mixed with the curable resin (A) from the viewpoint of being able to disperse more uniformly and easily improve the mechanical properties and thermal properties of the cured product. It is preferable to do this.

(Characteristics of modified cellulose nanofiber (B))
The modified cellulose nanofiber (B) obtained using the catalyst usually has a powdery form and is excellent in handleability. Moreover, even if the modification ratio (bonding amount or modification rate) of the fluorene compound (B1) is relatively small, the modified cellulose nanofiber (B) often has a powdery form.

The ratio (modification rate) of the fluorene compound (B1) bonded to the cellulose nanofiber (B2) is, for example, 0.01 to 25% by weight (for example, 1 to 20) with respect to the total amount of the modified cellulose nanofiber (B). The weight may be selected from the range of about 2 to 20% by weight (3 to 18% by weight), and preferably about 5 to 15% by weight (for example, 10 to 15% by weight). In particular, when the group X ^{1 of} the fluorene compound (B1) is a group — [(OA) _m1 —Y ¹ ] (wherein Y ¹ represents a hydroxyl group), the modification rate is the modified cellulose nanofiber (B ) In the range of about 0.01 to 20% by weight, for example, 0.05 to 15% by weight, preferably 0.1 to 10% by weight (for example, 0.3 to 7% by weight) ), More preferably about 0.5 to 5% by weight (especially 0.7 to 3% by weight). Moreover, group ^{X 1} is a group of the fluorene compound (B1) - if it is ^{_{[(OA) m1 -Y 1]}} ( in the formula, shown ^{Y 1} is a glycidyloxy group), wherein the modification ratio is, for example, 0.01 ˜25 wt% (eg, 0.1-20 wt%), preferably 1-18 wt% (eg, 3-17 wt%), more preferably 5-15 wt% (especially 10-13 wt%) It may be a degree.

  If the modification rate is too large, properties such as dispersibility in an aqueous solvent and low linear thermal expansion coefficient may be deteriorated. On the other hand, if the modification rate is too small, a powdery form cannot be formed, and handling properties are likely to deteriorate. Or dispersibility (affinity or miscibility) with the curable resin (A) in the curable composition may be reduced. The modification rate can be measured by the method described in Examples described later.

  The average fiber diameter of the modified cellulose nanofiber (B) is, for example, 1 to 1000 nm (for example, 3 to 800 nm), preferably 5 to 500 nm (for example, 7 to 300 nm), more preferably 10 to 200 nm (particularly 20 to 200 nm). 100 nm). If the average fiber diameter is too large, properties such as strength of the cured product may be deteriorated. The maximum fiber diameter of the modified cellulose nanofiber (B) is, for example, 3 to 1000 nm (for example, 5 to 900 nm), preferably 10 to 700 nm (for example, 50 to 500 nm), and more preferably 70 to 400 nm (particularly 100). About 300 nm). In many cases, the modified cellulose nanofiber (B) does not substantially contain a cellulose fiber having a fiber diameter of micrometer size.

  The average fiber length of the modified cellulose nanofiber (B) can be selected, for example, from a range of about 0.01 to 500 μm (for example, 0.1 to 400 μm), and usually 1 μm or more (for example, 5 to 300 μm), preferably It may be 10 μm or more (for example, 20 to 200 μm), more preferably 30 μm or more (particularly 50 to 150 μm). If the average fiber length is too short, the mechanical properties of the cured product may be reduced. Conversely, if the average fiber length is too long, the dispersibility in the curable composition may be reduced.

  The ratio (aspect ratio) of the average fiber length to the average fiber diameter of the modified cellulose nanofiber (B) is, for example, 5 or more (for example, about 5 to 10000), preferably 10 or more (for example, about 10 to 5000), Preferably, it may be 20 or more (for example, about 20 to 3000), particularly 50 or more (for example, about 50 to 2000), 100 or more (for example, about 100 to 1000), and further 200 or more (for example, 200 to 200). About 800). Further, if the aspect ratio is too small, the reinforcing effect on the resin is lowered, and if the aspect ratio is too large, uniform dispersion becomes difficult and the fibers may be easily decomposed (or damaged).

  In the present specification and claims, the average fiber diameter, average fiber length, and aspect ratio of the modified cellulose nanofiber (B) (or the raw material cellulose nanofiber (B2)) are based on an image of a scanning electron micrograph. It may be calculated by selecting 50 fibers at random and averaging them.

  The modified cellulose nanofiber (B) has a low water content because the hydrophobicity is improved by the modification of the fluorene compound (B1). That is, the moisture content is 0 to 7% by weight (for example, 0 to 5% by weight), preferably 0.1 to 5% by weight when left standing for one day and night under conditions of a temperature of 25 ° C. and a humidity of 60%. Preferably, it may be about 0.3 to 3% by weight. The water content can be measured using a near infrared analyzer or the like.

  The bulk density (apparent density) of the modified cellulose nanofiber (B) is, for example, 0.01 to 0.7 g when measured according to JIS K7365-1999 under conditions of a temperature of 25 ° C. and a humidity of 60%. / Ml, preferably 0.05 to 0.5 g / ml, more preferably about 0.1 to 0.3 g / ml. The bulk density P can be calculated from the formula P = W / V by measuring the volume V of a modified cellulose nanofiber having a predetermined weight W in a measuring cylinder.

  The modified cellulose nanofiber (B) has high fluidity and an angle of repose measured according to JIS R9301-2-2 under conditions of a temperature of 25 ° C. and a humidity of 60%, for example, 20 to 45 °. The angle may be preferably 25 to 40 °, more preferably about 30 to 35 °. If the fluidity is too large, the handleability is lowered. Conversely, if the fluidity is too small, the dispersibility may be lowered.

  The modified cellulose nanofiber (B) maintains the nanofiber form without forming a viscous liquid. Therefore, the molecular weight (or degree of polymerization) is relatively large, and the viscosity average degree of polymerization may be, for example, 100 to 10,000, preferably 200 to 5000, more preferably about 300 to 2000.

  The viscosity average degree of polymerization can be measured by a viscosity method described in TAPPI T230. That is, 0.04 g of modified cellulose nanofiber (or raw material cellulose nanofiber) is precisely weighed, 10 mL of water and 10 mL of 1M copper ethylenediamine aqueous solution are added, and stirred for about 5 minutes to dissolve the modified cellulose nanofiber. The obtained solution is put into an Ubbelohde type viscosity tube, and the flow rate is measured at 25 ° C. A mixed liquid of 10 mL of water and 10 mL of 1M copper ethylenediamine aqueous solution is measured as a blank. Using the intrinsic viscosity [η] calculated based on these measured values, the viscosity average degree of polymerization can be calculated according to the following formula described in the Wood Science Experiment Manual (edited by the Wood Society of Japan, Buneidou Publishing).

      Viscosity average degree of polymerization = 175 × [η]

  Further, in the curable composition or cured product of the present invention, when the properties of the modified cellulose nanofiber (B) (for example, strength, low linear thermal expansion properties, heat resistance, etc.) are effectively expressed, the modification is highly crystalline. Cellulose nanofibers are preferred. As described above, the modified cellulose can maintain the crystallinity of the cellulose nanofibers, and therefore the crystallinity of the modified cellulose nanofiber (B) can directly refer to the value of the cellulose nanofibers. For example, the crystallinity of the modified cellulose is 40 to 95% (for example, 50 to 85%), preferably 60 to 95% (for example, 65 to 85%), more preferably 70 to 90% (particularly 75 to 90%). %) Or a crystallinity of 60% or more (for example, about 75 to 90%). If the degree of crystallinity is too small, characteristics such as linear thermal expansion characteristics and strength may be deteriorated. Examples of the crystal structure of cellulose include type I, type II, type III, type IV, and the like, and type I crystal structures exhibiting low linear expansion characteristics and high elastic modulus are preferable. The crystallinity can be measured by a conventional method.

  The ratio of the modified cellulose nanofiber (B) can be selected from a range of, for example, about 0.01 to 50 parts by weight (for example, 0.05 to 40 parts by weight) with respect to 100 parts by weight of the curable resin (A). For example, it may be about 0.1 to 30 parts by weight (for example, 0.5 to 25 parts by weight), preferably about 1 to 20 parts by weight (for example, 2 to 15 parts by weight). It may be in a range of about parts by weight (for example, 4 to 8 parts by weight), for example, about 4 to 6 parts by weight.

  Moreover, the ratio of a modified cellulose nanofiber (B) is 0.01-50 volume% (for example, 0.1-30) with respect to the total amount of solid content except the solvent mentioned later among curable compositions, for example. For example, 0.5 to 20% by volume (for example, 0.8 to 15% by volume), preferably about 1 to 10% by volume (for example, 1 to 8% by volume). Usually, it may be in the range of about 1.5 to 5% by volume (1.5 to 3.5% by volume), for example, about 2 to 3% by volume.

  If the proportion of the modified cellulose nanofiber (B) is too small, the mechanical properties of the cured product may be lowered, or the thermal expansion coefficient may not be reduced. On the other hand, if the amount is too large, the handleability of the curable composition may be reduced.

[Other ingredients]
In addition to the curable resin (A) and the modified cellulose nanofiber (B), the curable composition of the present invention may further contain other components, for example, a curing agent, a curing accelerator, a solvent, a dispersing agent, or the like. It may contain a compatibilizing agent, an additive and the like.

(Curing agent)
The curing agent can be selected according to the type of the curable resin (A). For the phenol resin, for example, hexamethylenetetramine (hexamine), paraformaldehyde, formaldehyde derivatives such as 1,3,5-trioxane, formalin, and the like can be used. Can be mentioned.

  When the curable resin (A) is a resin having a polymerizable unsaturated bond [unsaturated polyester resin, vinyl ester resin (epoxy (meth) acrylate resin), multifunctional (meth) acrylate resin, etc.], for example, And thermal polymerization initiators (thermal radical generators). Examples of the thermal polymerization initiator include organic peroxides [eg, dialkyl peroxides (eg, di-t-butyl peroxide), diacyl peroxides (eg, lauroyl peroxide, benzoyl peroxide, etc.), Peracids (or peracid esters) (for example, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peracetate, etc.), ketone peroxides, peroxycarbonates, peroxyketals, etc.], azo And compounds [for example, azonitrile compounds such as 2,2′-azobis (isobutyronitrile), azoamide compounds, azoamidine compounds, etc.] and the like.

  When the curable resin (A) is an epoxy resin, for example, an amine-based curing agent [in particular, a primary amine such as a chain aliphatic amine (for example, a chain such as ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine) Cyclic aliphatic amines); cycloaliphatic amines (eg mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, 3,9-bis (3-aminopropyl) -2,4, Monocyclic or spirocycloaliphatic polyamines such as 8,10-tetraoxaspiro [5.5] undecane; bridged cyclic polyamines such as norbornanediamine; araliphatic polyamines such as xylylenediamine; Aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, , 4'-diaminodiphenyl sulfone, etc.]]; polyaminoamide-based curing agents [condensates of polyethylene polyamines such as ethylenediamine, diethylenetriamine, triethylenehexamine, dimer acid, and fatty acid as necessary]; acid anhydride Physical curing agents [for example, aliphatic acid anhydrides such as dodecenyl succinic anhydride and polyadipic anhydride; tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl anhydride Alicyclic acid anhydrides such as highmic acid and methylcyclohexene tetracarboxylic dianhydride; aromatic acid anhydrides such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenone tetracarboxylic acid anhydride ]; Phenolic resin hardener (example) If, phenol novolak resin, novolak resins such as cresol novolak resin, such as resol-type phenol resin) and the like. These curing agents can be used alone or in combination of two or more. Of these curing agents, phenol resin-based curing agents such as phenol novolac resins are widely used.

  The proportion of the functional group (or active hydrogen) of the curing agent is, for example, 0.1 to 4 equivalents, preferably 1 equivalent to 1 equivalent of the reactive site of the curable resin (A) (for example, the epoxy group of the epoxy resin). It may be about 0.3 to 2 equivalents, more preferably about 0.5 to 1.5 equivalents (for example, 0.8 to 1.2 equivalents), and usually about 0.9 to 1.1 equivalents. May be.

(Curing accelerator)
A hardening accelerator can also be suitably selected according to the kind of curable resin (A). Typical curing accelerators include epoxy resin curing accelerators such as amines [eg, tertiary amines (eg, triethylamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl ) Phenol, 1,8-diazabicyclo [5.4.0] -7-undecene, etc.]; imidazoles (eg mono- or dialkylimidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole; 2-phenyl) Aryl imidazoles such as imidazole) and derivatives thereof (for example, salts such as phenol salts, phenol novolak salts, carbonates, formate salts, etc.); alkali metal or alkaline earth metal alkoxides; phosphines; amide compounds (dimer acid polyamides) Such) Lewis acid complex compound (such as boron trifluoride / ethylamine complex); sulfur compound (such as polysulfide, mercaptan compound (thiol compound)); boron compound (such as phenyldichloroborane); condensable organometallic compound (organic titanium compound, organoaluminum) Compound, etc.). These curing accelerators may be used alone or in combination of two or more. Among these curing accelerators, amines such as imidazoles (for example, 2-ethyl-4-methylimidazole) are widely used.

  The ratio of the curing accelerator is, for example, 0.01 to 30 parts by weight, preferably 0.05 to 20 parts by weight, and more preferably 0 to 100 parts by weight of the curable resin (A) (for example, epoxy resin). It may be about 1 to 10 parts by weight (for example, 0.1 to 5 parts by weight).

(solvent)
The curable composition of the present invention contains a solvent (solvent or dispersion medium) and may be in the form of a paint or an impregnating liquid (or varnish). Especially as a solvent, as long as it can melt | dissolve or disperse | distribute the structural component [For example, curable resin (A), a modified cellulose nanofiber (B), a hardening agent etc., especially a modified cellulose nanofiber (B)] of a curable composition. Without limitation, for example, hydrocarbons (for example, aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as toluene and xylene); halogenated hydrocarbons (for example, , Methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene, etc.); ethers (eg, chain ethers such as diethyl ether and diisopropyl ether, cyclic ethers such as tetrahydrofuran, 1,4-dioxane, etc.); ketones (eg, , Acetone, methyl ethyl ketone, cyclohexanone, etc.); esters (for example, Methyl acid, such as acetic acid _{C 1-4} alkyl, such as butyl acetate); glycols (e.g., ethylene glycol, (poly, such as dipropylene _glycol), such as _{C 2-4} alkylene glycol); glycol ethers [e.g., cellosolves ( For example, methyl cellosolve, ethyl cellosolve, etc.), carbitols (eg, carbitol etc.), (poly) _C2-4 alkylene glycol (mono or di) _C1-4 alkyl ether etc. such as dipropylene glycol dimethyl ether, etc.]; glycol ether acetates (e.g., propylene glycol monomethyl ether acetate, (poly) C _2-4 alkylene glycol mono C _1-4 alkyl ether acetates such as diethylene glycol monobutyl ether acetate); sulfoxy Class (e.g., dimethyl sulfoxide), amides (e.g., dimethylformamide, dimethylacetamide, etc. N- methylpyrrolidone), and the like. These solvents may be used alone or in combination of two or more as a mixed solvent. Of these solvents, ketones such as methyl ethyl ketone are widely used.

  When the solvent is included, the solid content concentration of the curable composition is not particularly limited, and may be adjusted so that the curable composition exhibits a desired fluidity, for example, 0.1 to 70% by weight (for example, 1 to 1%). 60% by weight).

(Dispersant or compatibilizer)
As the dispersing agent or compatibilizing agent, a conventional dispersing agent or compatibilizing agent used when dispersing the cellulose fiber in the resin can be used. From the viewpoint of excellent dispersibility, the modified cellulose nanofiber (B) is used. The constituting fluorene compound (B1) is preferred. In the case where the modified cellulose nanofiber (B) is produced by reacting the raw cellulose nanofiber (B2) and the fluorene compound (B1) in the process of mixing the raw cellulose nanofiber (B2) and the raw cellulose nanofiber (B2), The fluorene compound (B1) remaining without reacting may be used.

  The ratio of the dispersant or the compatibilizer may be, for example, 10% by weight or less (for example, about 0.01 to 10% by weight), for example, 5% by weight or less, preferably 3% by weight with respect to the entire solid content. % Or less, more preferably 1% by weight or less.

(Additive)
Additives include conventional additives such as flame retardants (phosphorous flame retardants, halogen flame retardants, inorganic flame retardants, etc.), flame retardant aids, flexibilizers, plasticizers, lubricants, surfactants. , Fillers (silica, talc, mica, etc.), colorants (for example, dyes and pigments), stabilizers (thermal stabilizers, antioxidants, UV absorbers, etc.), conductive agents, antistatic agents, flow regulators, Examples include leveling agents, antifoaming agents, surface modifiers, nucleating agents, crystallization accelerators, antibacterial agents, preservatives, thermal or photopolymerization initiators, polymerization inhibitors, and the like. The ratio of these additives is, for example, 10% by weight or less (for example, about 0.01 to 5% by weight), preferably 3% by weight or less (for example, 0.1 to 1% by weight) with respect to the entire solid content. Degree).

[Method for producing curable composition]
The curable composition of the present invention comprises a curable resin (A), a modified cellulose nanofiber (B) and / or a raw material thereof (a component that forms the modified cellulose nanofiber (B)), and, if necessary, the above-described components. It can be prepared by a method including a mixing step of mixing and dispersing other components with a mixer or a stirrer.

  Examples of the mixer or agitator include a ball mill, a tumble mixer, a ribbon blender, a Henschel mixer, a mixing roll, a kneader, and a Banbury mixer. Of these, they are often mixed by a ball mill.

  When mixing with a ball mill, for example, it may be performed at a rotational speed of about 10 to 500 rpm, preferably about 30 to 150 rpm (particularly 40 to 120 rpm).

  The mixing temperature may be a temperature at which the curable resin (A) (for example, thermosetting resin) is not completely cured, and is, for example, -20 to 100 ° C, preferably 0 to 70 ° C, more preferably 10 to 10 ° C. It may be about 50 ° C. (for example, 25 ° C.). Although mixing time is not specifically limited, For example, 1 minute-24 hours, Preferably it is 0.5-6 hours, More preferably, about 1-3 hours may be sufficient.

[Production method and characteristics of prepreg and cured product]
(Prepreg)
Since the modified cellulose nanofiber (B) is uniformly dispersed in the curable composition thus obtained, the cured product of the curable composition has excellent mechanical properties and thermal properties. ing. The cured product may be prepared by curing the curable composition with heat and / or light energy. However, from the viewpoint of further improving mechanical properties and thermal properties, the curable composition ( For example, a prepreg including a solid content excluding a solvent) and a second fibrous reinforcing material other than the modified cellulose nanofiber (B) is formed, and the prepreg is cured by heat and / or light energy to be cured. Is often prepared.

  Examples of the second fibrous reinforcing material include polyamide fibers (aliphatic polyamide fibers such as nylon 6 fiber and nylon 66 fiber, poly (p-phenylene terephthalamide) fiber, poly (m-phenylene terephthalamide) fiber, and the like. Aramid fibers), polyester fibers (for example, polyalkylene arylate fibers such as polyethylene terephthalate fibers), and cellulose fibers other than modified cellulose nanofibers (B) (for example, pulp, unmodified cellulose nanofibers (B2), etc.) Organic fibers such as glass fibers, carbon fibers, boron fibers, whiskers, and wollastonite may be used. These 2nd fibrous reinforcements can also be used individually or in combination of 2 or more types. Of these second fibrous reinforcing materials, inorganic fibers (for example, glass fibers, carbon fibers, particularly glass fibers) are generally used.

  The average fiber diameter of the second fibrous reinforcing material varies depending on the type of fiber, but can be selected from a range of about 0.1 to 1000 μm (for example, 0.5 to 500 μm), for example, 1 to 100 μm (for example, 2 to 50 μm), preferably 3 to 20 μm, more preferably about 5 to 10 μm.

  The second fibrous reinforcing material may be a short fiber, but is usually a long fiber in many cases. The second fibrous reinforcing material may be in the form of a fabric. Examples of the fabric include woven fabric, knitted fabric, and non-woven fabric. The structure of the cloth can be appropriately selected according to the type of the cloth. In the case of the woven cloth, for example, plain weave, twill weave, satin weaving and the like can be mentioned. In the case of the knitted cloth, for example, warp knitting (tricot etc.) Flat, Kanoko, etc.). The second fibrous reinforcing material may be surface-treated.

  When the second fibrous reinforcing material is a fabric, the average thickness can be selected from a range of about 10 to 300 μm (for example, 20 to 250 μm), for example, 30 to 200 μm (for example, 50 to 150 μm), preferably May be about 70 to 130 μm (for example, 80 to 120 μm).

  In the prepreg, the ratio of the curable composition (solid content excluding the solvent) is, for example, 55 to 300 parts by weight (for example, 60 to 250 parts by weight) with respect to 100 parts by weight of the second fibrous reinforcing material. Preferably, it may be about 65 to 200 parts by weight (for example, 70 to 150 parts by weight), more preferably about 80 to 130 parts by weight (for example, 90 to 110 parts by weight). In addition, you may adjust the said ratio suitably according to the use and thickness of a prepreg. For example, when the thickness of the second fibrous reinforcing material is about 100 μm (for example, 90 to 110 μm) and the prepreg is for the core, the ratio of the curable composition (solid content) is the second fibrous reinforcing material. For example, it may be about 70 to 130 parts by weight (for example, 80 to 125 parts by weight) with respect to 100 parts by weight, and the thickness of the second fibrous reinforcing material is about 100 μm (for example, 90 to 110 μm). When the prepreg is for multilayer lamination (prepreg for multilayer lamination), the ratio of the curable composition (solid content) is, for example, 90 to 170 parts by weight (100 to 100 parts by weight of the second fibrous reinforcing material). For example, it may be about 100 to 150 parts by weight. In the prepreg, the ratio of the second fibrous reinforcing material is, for example, about 35 to 60% by volume, preferably about 40 to 55% by volume, and more preferably about 45 to 50% by volume with respect to the entire prepreg. There may be. When there are too few curable compositions (solid content) and 2nd fibrous reinforcement, there exists a possibility that the cured | curing material excellent in the mechanical characteristic and the thermal characteristic cannot be prepared.

  Depending on the form of the second fibrous reinforcing material, the prepreg may be in the form of a UD prepreg in which a plurality of second fibrous reinforcing materials are aligned in one direction. It may be in the form of a cross prepreg containing a curable composition (solid content) between the reinforcing materials. The curable resin contained in the prepreg may be in an uncured state or a semi-cured state (B stage).

  Such a prepreg can be prepared by, for example, a method in which the curable composition is used as an impregnating liquid (or varnish), the second fibrous reinforcing material is impregnated with the impregnating liquid, and the solvent is dried as necessary. . A drying temperature can be suitably selected according to the kind of solvent, for example, 50-250 degreeC, Preferably it may be about 100-150 degreeC (for example, 110-130 degreeC) grade. The drying time is not particularly limited as long as the curable resin (A) is not completely cured, and may be, for example, about 0.5 to 60 minutes, preferably about 1 to 30 minutes. Drying may be performed under normal pressure or reduced pressure.

(Cured product)
By curing the curable composition or the prepreg with heat and / or light energy (usually heat energy), a cured product having excellent mechanical properties and thermal properties can be prepared.

  When performing the curing treatment by heating, the heating temperature can be appropriately selected according to the type of the curable resin (A), and is, for example, 80 to 300 ° C, preferably 120 to 250 ° C, more preferably 150 to 200 ° C. (For example, 170-190 degreeC) grade may be sufficient. The heating time may be, for example, 0.5 to 6 hours, preferably 1 to 3 hours. The heating may be performed by raising the temperature stepwise.

  Moreover, you may perform a hardening process, pressurizing with a press etc. FIG. The molding pressure may be, for example, about 0.1 to 15 MPa, preferably about 0.5 to 10 MPa. The molding pressure may be increased or decreased stepwise depending on the heating temperature, etc.For example, the molding pressure is increased in accordance with the minimum melt viscosity of the resin to eliminate voids in the prepreg, and after a certain time has elapsed. The pressure may be lowered.

  The shape of the cured product is not particularly limited, and may be a one-dimensional shape (bar shape, etc.), a two-dimensional shape (sheet shape, film shape, plate shape, etc.), a three-dimensional shape [for example, block shape, rod shape, hollow shape ( [Tubular or tube-like]. Typical molding methods include hand lay-up method (HLU method), spray-up method (SPU method), vacuum bag method, pressurized bag method, autoclave method, resin injection method (RTM method), matched die method, sheet molding. Examples thereof include a compound method (SMC method), a bulk molding compound method (BMC method), a filament winding method (FW method), a pultrusion method (pultrusion method), and a continuous lamination method. When forming a cured product using the prepreg, the prepreg may be cured alone, but usually a plurality of (for example, 2 to 10, preferably about 3 to 5) prepregs are laminated and press-molded. Often a cured product (or laminate) is prepared. When laminating a plurality of prepregs, the directions of the fibers of the second fibrous reinforcing material included in each prepreg may or may not be aligned between the prepregs.

  Since the modified cellulose nanofiber (B) is uniformly dispersed in the curable resin (A), the cured product of the present invention has high mechanical properties (such as tensile strength and bending strength) and a low coefficient of thermal expansion. doing. In particular, the modified cellulose nanofiber (B) and the thermoplastic resin may be used for combining the modified cellulose nanofiber (B) and the curable resin (A), or even if the amount of the modified cellulose nanofiber (B) is small. Surprisingly, it seems that mechanical properties (particularly, tensile strength, etc.) can be remarkably improved as compared with the case of combining them. The volume ratio of the modified cellulose nanofibers (B) in the cured product may be the same as the volume ratio of the modified cellulose nanofibers (B) with respect to the total amount of solids exemplified in the above-mentioned section of the curable composition. Moreover, when using the said prepreg, the volume ratio of the modified cellulose nanofiber (B) with respect to the whole hardened | cured material may be 0.1-10 volume%, for example, Preferably about 0.5-5 volume%, Usually, it may be about 1 to 2% by volume.

  The bending strength in the cured product prepared using the epoxy resin as the curable resin (A) and the glass fiber as the second fibrous reinforcing material is, for example, 300 to 500 MPa, preferably 330 to 450 MPa, more preferably. It may be about 350 to 400 MPa. The maximum tensile strength may be, for example, about 150 to 300 MPa, preferably about 200 to 270 MPa, and more preferably about 220 to 250 MPa.

  The coefficient of thermal expansion (in the plane direction) of the cured product prepared using the epoxy resin as the curable resin (A) and the glass fiber as the second fibrous reinforcing material is, for example, 30 ppm / ° C. or less, preferably 25 ppm. / ° C. or less, more preferably 20 ppm / ° C. or less (for example, about 14 to 16 ppm / ° C.).

  Although it is known that when the cured product contains a filler, the adhesiveness is usually lowered, the cured product of the present invention has unexpectedly improved adhesion (or adhesion) with a metal (for example, copper). Are better. The copper foil peeling strength (copper foil peeling strength) in the cured product prepared using the epoxy resin as the curable resin (A) and the glass fiber as the second fibrous reinforcing material is, for example, 1. It may be 5 to 2.5 kN / m, preferably 1.7 to 2.2 kN / m, more preferably about 1.8 to 2 kN / m.

  In the present specification and claims, the volume ratio, the bending strength, the tensile maximum strength, the thermal expansion coefficient (in the plane direction), and the copper foil peeling strength of the modified cellulose nanofiber (B) are described in the examples described later. It can measure by the method of description.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Below, it shows about the evaluation method and the used raw material.

[Evaluation method]
(Proportion of fluorene compound bonded to modified cellulose nanofiber (modification rate))
The modification rate of the fluorene compound (hereinafter also referred to as the fluorene modification rate) is determined by performing a Raman analysis using a Raman microscope (XORIRA, manufactured by HORIBA JOBIN YVON), and the aromatic ring (1604 cm ⁻¹ ) and CH within the ring of cellulose. It calculated by the intensity ratio (I ₁₆₀₄ / I ₁₃₇₅ ) of the absorption band with (1375 cm ⁻¹ ). In the calculation, a diacetyl cellulose (manufactured by Daicel Corporation) film containing a predetermined amount of a fluorene compound was prepared by a solution cast method, and a calibration curve prepared from these strength ratios (I ₁₆₀₄ / I ₁₃₇₅ ) was used. It was. All samples were measured three times, and the average value calculated from the results was defined as the fluorene modification rate.

(Volume ratio of cellulose fiber in the laminate)
The volume ratio of the cellulose fiber in the laminate is obtained by measuring the weight of the 10 cm square laminate and subtracting the weight of the glass cloth calculated from the basis weight from this weight to obtain a resin composition (cellulose fiber, curable resin). The weight of the cured product containing a curing agent and a curing accelerator) was calculated. The volume ratio of the resin composition in the laminate was calculated by calculating the respective volumes from the specific gravity of the resin composition and the glass cloth. From the blending ratio of the cellulose fibers at the time of varnish preparation, the volume ratio of the cellulose fibers in the resin composition is calculated, and by multiplying this value by the volume ratio of the resin composition in the laminate, the cellulose in the laminate is obtained. The fiber volume fraction was calculated.

(Bending strength)
The bending test was measured according to JIS C 6481 (1996) using Minebea's “LTS-1kNB”. The thickness h and width w of the sample were measured in units of 0.01 mm. Next, the sample was supported at a distance between fulcrums (16 h ± 0.5 mm), and a force was applied to the central portion with a pressurizing tool, and the force when the sample was broken was measured with an accuracy of 1N. The speed at which force was applied to the sample was 2 h ± 0.2 mm / min.

(Maximum tensile strength)
The tensile test was measured based on JIS K 6911 (1995) using Minebea's “LTS-1kNB”. The central width (Wc) and thickness (t) between the test specimens were accurately measured with an outer micrometer to 0.01 mm. The other dimensions were measured with calipers and confirmed to be within the specified dimensions. The distance between the grips was 115 ± 5 mm. The test piece was attached to the gripper so that the point of action of the force coincided with the central axis of the test piece. A load was applied to the test piece at a rate of 5 ± 1 mm / min, and the load when fractured at almost the center of the test piece was measured up to 10 N (1 kgf).

(Coefficient of thermal expansion (plane direction))
The thermal expansion coefficient was measured by the TMA method according to JIS C 6481 (1996) using “TMA-60” manufactured by Shimadzu Corporation. The thickness of the copper clad laminate from which the sample was taken was at least 0.8 mm. Note that the sample collection portion is a position representative of the copper-clad laminate. After removing the copper foil, the sample was cut into 6 ± 2 mm square using a cutting machine such as a precision cutter that does not peel off the cut surface. The sample was dried for 1 hour at a temperature of 80 ± 3 ° C. after cutting. After drying, the cut surface was lightly polished with abrasive paper (P800, P1000 or P1200), and the flash was removed. The front and back surfaces that contact the sensor were also lightly polished with abrasive paper to make it flat. The sample was set in a holder, and a probe (stylus) was brought into contact with the sample surface facing the measurement direction. After confirming that the probe was firmly in contact with the sample, a load of 2 g was applied. The initial temperature was at least 10 ° C. lower than the measurement temperature range, and the standard rate of temperature increase was 2 ° C./min. The thermal expansion coefficient a was determined for the linear portion (Tg or less) of temperature and elongation (or shrinkage) within the measurement temperature range by the following formula. In addition, it measured by the same method about three samples, the thermal expansion coefficient was averaged, and it was set as the thermal expansion coefficient.

a = (L ₂ −L ₁ ) / [(T ₂ −T ₁ ) × L ₁ ]
(Where a is the thermal expansion coefficient [K ⁻¹ ], L ₁ is the initial length [mm], L ₂ is the final length [mm], T ₁ is the initial temperature [K], and T ₂ is the final temperature [ K]).

(Copper foil peel strength (copper foil peel strength))
Copper foil peeling strength was measured based on JIS C 6481 (1996) using “LTS-1kNB” manufactured by Minebea. The sample was prepared by cutting a copper clad laminate into a size of 25 mm × 100 mm, leaving a copper foil having a width of 10 ± 0.1 mm at the center in the width direction on one side, and removing the copper foil on both sides. After stripping one end of the copper foil to an appropriate length, the sample was attached to a support fitting, and the tip of the peeled copper foil was gripped with a gripping tool. The copper foil was continuously peeled off by about 50 mm at a speed of about 50 mm / min in the direction in which the tensile direction was perpendicular to the copper foil surface. The minimum load during this period was taken as the peel strength, and the unit was expressed in kN / m. When the copper foil was cut, a retest was performed. In addition, when the plate | board thickness of the sample was thin and measurement was difficult, the sample was fixed to the appropriate plate.

[Raw materials]
BPFG: 9,9-bis (4-glycidyloxyphenyl) fluorene modified cellulose nanofiber (B-CNF): prepared according to Synthesis Example 1 described later Epoxy resin: “Ep828” manufactured by Mitsubishi Chemical Corporation
Curing agent: “TD2090” manufactured by DIC Corporation, phenol novolac resin.

[Synthesis Example 1]
100 g of an aqueous dispersion of cellulose nanofibers (solid concentration 15% by weight) was dispersed in 500 g of N, N-dimethylacetamide (DMAc) and centrifuged, and then the precipitated solid was further dispersed in 500 g of DMAc and again. Centrifugation gave a solvent substitution to obtain a mixture of cellulose nanofibers and DMAc (cellulose content about 10% by weight). This mixture was transferred to a 1000 mL three-necked flask, and 350 g of DMAc, 15 g of BPFG, and 10 g of diazabicycloundecene (DBU) were added, and the mixture was stirred at 120 ° C. for 3 hours. The obtained liquid mixture was collected by centrifugation, and the process of washing with 1200 mL of DMAc was repeated three times to obtain modified cellulose nanofibers (B-CNF). The modification ratio of the fluorene compound was 12.55% by weight. In addition, the observation image by the scanning electron microscope (SEM) [JEOL Co., Ltd. product "JSM-6510"] of the cellulose nanofiber which is the used raw material is shown in FIG.

[Example 1]
Weigh 30.287 g of epoxy resin and 17.098 g of curing agent (amount in which the proportion of hydroxyl groups in the phenol novolac resin is about 1 equivalent to the epoxy groups in the epoxy resin) into a container, and add methyl ethyl ketone (MEK) 106. 964 g was stirred and dissolved at room temperature. After dissolving the resin, 0.486 g of 2-ethyl-4-methylimidazole (2E4MZ) as a curing accelerator (or catalyst) and 1.519 g of B-CNF obtained in Synthesis Example 1 (modification rate of 12.55%) In addition, the mixture was stirred at room temperature. In addition, the volume ratio (or volume fraction) of B-CNF with respect to the whole solid content [component except a solvent (MEK)] of this mixture is 2.5 volume%. A zirconia ball having a diameter of 10 mm was added to this mixture, and ball mill mixing was performed at 200 rpm for 2 hours until the mixture became uniform. After mixing, the balls were removed with a sieve to obtain a curable composition (varnish).

  The obtained varnish (10.373 g) was placed in a vat, and a glass cloth (IPC (The Institute for Interconnecting and Packaging Electronic Circuits) standard: # 2116) cut to 200 mm × 150 mm was dipped in the varnish. A glass cloth immersed in an oven set at 120 ° C. was suspended and dried for 3 minutes to obtain a prepreg. In the obtained prepreg, the ratio of the solid content derived from the varnish was 100 parts by weight with respect to 100 parts by weight of the glass cloth. Moreover, the ratio of the glass cloth was 52 volume% with respect to the whole prepreg. The same operation was repeated four times to prepare four prepregs, and the obtained prepregs were cut into 150 mm squares, and the four prepregs were laminated without particularly adjusting the fiber direction of the glass cloth. A 200 mm square (1.5 mm thick) stainless steel mirror plate is prepared, on which the roughened surface of copper foil ("CF-T9LK" (thickness 18 µm) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) is placed. And a prepreg laminated thereon was stacked thereon. The copper foil was further laminated on the prepreg with the roughened surface facing down, and a 200 mm square stainless steel mirror plate (thickness: 1.5 mm) was further laminated thereon. This laminate was cured by heating and pressure using a vacuum press machine under conditions of 145 ° C./2 MPa / 10 minutes and then 180 ° C./0.2 MPa / 120 minutes to produce a copper-clad laminate.

  The obtained copper-clad laminate was cut into a predetermined sample shape according to the evaluation method, and each evaluation was performed by removing the copper foil by etching as necessary.

[Comparative Example 1]
A prepreg was produced in the same manner as in Example 1 except that B-CNF was not added, and a laminate was produced in the same manner as in Example 1.

[Comparative Example 2]
Pulp cut into chips of about 3 mm square (“Flow Flour (Grade 4800)” manufactured by GP Cellulose) was used so that the weight ratio of the pulp to water was 70:30. After this fiber is defibrated for 10 minutes at room temperature and 300 rpm using a twin screw extruder ("Lab Plast Mill" manufactured by Toyo Seiki Co., Ltd.) so that the average fiber length is about 100 µm. And dried to obtain cellulose nanofibers. A laminated board was produced in the same manner as in Example 1 except that the cellulose nanofibers were used instead of B-CNF.

[Comparative Example 3]
A laminated board was produced in the same manner as in Example 1 except that instead of B-CNF, pulp cut into chips of about 3 mm square (“Flow pulp (Grade 4800)” manufactured by GP Cellulose) was used. However, since the fiber diameter and fiber length of the pulp are large, it was not possible to produce a laminated board in which the pulp was uniformly dispersed without being dispersed in the varnish.

  Table 1 shows the evaluation results of the laminates obtained in Example 1 and Comparative Examples 1 to 3.

  As apparent from Table 1, Example 1 to which B-CNF was added resulted in bending strength and tensile strength exceeding those of Comparative Examples 1 to 3. This result shows that the modification of cellulose nanofibers (CNF) with a fluorene compound improves the dispersibility in solvents and the reactivity with the epoxy resin, thereby improving the adhesion between the epoxy resin and the B-CNF interface. it is conceivable that. On the other hand, in the comparative example 2, since the cellulose fiber is not modified with a fluorene compound, it is presumed that the affinity with the solvent and the epoxy resin is reduced, and the tensile strength and bending strength are reduced.

  In particular, with respect to tensile strength, when Example 1 using B-CNF, which is a modified cellulose nanofiber, was compared with Comparative Example 2 using unmodified cellulose nanofiber instead of B-CNF, Example 1 was As compared with Comparative Example 2, it was found to be as large as 31.4%, and it was found that even if the amount of cellulose fibers added was about 4.8% by weight with respect to the total amount of resin and cellulose fibers, it could be remarkably improved. On the other hand, in the Example of patent document 3, compared with the comparative example 2 which adds 10 weight% with respect to the total amount of resin and a cellulose fiber, unmodified cellulose nanofiber is added to polylactic acid which is a thermoplastic resin, modified cellulose nanofiber In Examples 4 and 5 in which is added, it is described that the tensile strength was improved by about 19% (Table 2 of Patent Document 3). That is, in the embodiment of the present invention in which the epoxy resin that is a thermosetting resin and the modified cellulose nanofiber are combined, the amount of cellulose nanofiber added is less than half that in the embodiment of Patent Document 3 combined with the thermoplastic resin. Nevertheless, surprisingly, the tensile strength could be greatly improved by 10% or more.

  Moreover, in Example 1 to which B-CNF was added, the coefficient of thermal expansion was also reduced compared to Comparative Example 1 in which no cellulose fiber was added.

  Furthermore, the adhesiveness with copper foil usually decreases when a filler is added. However, when Example 1 and Comparative Example 1 are compared, it is surprising that B-CNF is involved in the adhesiveness with the copper foil. Surprisingly, even when B-CNF is added, the copper foil peel strength decreases. There wasn't.

  Since the curable composition of the present invention can form a cured product having excellent mechanical properties (bending strength, tensile strength, etc.) and thermal properties (low thermal expansion coefficient), printed wiring board materials such as copper-clad laminates, etc. Can be used effectively.

Claims (14)

  A curable composition comprising a curable resin (A) and a modified cellulose nanofiber (B) to which a fluorene compound (B1) having an aryl group at the 9,9-position is bonded. The curable composition according to claim 1, wherein the fluorene compound (B1) is a compound represented by the following formula (1).
(In the formula, ring Z is an arene ring, R ¹ and R ² are substituents, X ¹ is a heteroatom-containing functional group, k is an integer of 0 to 4, n is an integer of 1 or more, and p is an integer of 0 or more. Show) In the formula (1), X ¹ is a group-[(OA) _m1 -Y ¹ ] (wherein A is an alkylene group, Y ¹ is a hydroxyl group or a glycidyloxy group, and m1 represents an integer of 0 or more). The curable composition according to claim 2.   The ratio of a fluorene compound (B1) is 0.01-25 weight% with respect to the total amount of a modified cellulose nanofiber (B), The curable composition in any one of Claims 1-3.   The average fiber diameter of a modified cellulose nanofiber (B) is 5-500 nm, The curable composition in any one of Claims 1-4.   Curable resin (A) is an epoxy resin, The curable composition in any one of Claims 1-5.   The ratio of a modified cellulose nanofiber (B) is 0.1-20 weight part with respect to 100 weight part of curable resin (A), The curable composition in any one of Claims 1-6.   The curable composition according to any one of claims 1 to 7, further comprising a solvent.   The sclerosis | hardenability in any one of Claims 1-9 including the mixing process which mixes the component which forms curable resin (A), a modified cellulose nanofiber (B), and / or a modified cellulose nanofiber (B). A method for producing a composition, wherein the components forming the modified cellulose nanofiber (B) are a fluorene compound (B1) and an unmodified cellulose nanofiber (B2).   A prepreg further comprising a curable composition according to any one of claims 1 to 7 and a second fibrous reinforcing material other than the modified cellulose nanofiber (B).   The prepreg according to claim 10, wherein the second fibrous reinforcing material is an inorganic fiber.   Hardened | cured material which the prepreg of Claim 10 or 11 hardened | cured.   The hardened | cured material of Claim 12 whose volume ratio of a modified cellulose nanofiber (B) is 0.1-10 volume% with respect to the whole hardened | cured material. The cured product according to claim 12 or 13, which is a printed wiring board material.